This invention relates to devices for cleaning insides of tubes or pipes, such as those found in heat exchangers, condensers, and other applications where tubes are susceptible to scale build-up, bio-fouling, or other heat-transfer-inhibiting deterioration.
Heat exchangers for steam turbines have anywhere from 3,500 to 70,000 tubes therein, each being from 20 to 115 feet long. The efficacy of these tubes as heat exchangers, depends to a large extent, on the speed with which heat is transferred through their walls. "Build-up" on interior surfaces of the walls of these tubes detracts from their ability to transfer heat. Thus, tube cleaning devices are used to clean interior surfaces of such tubes, as well as of other tubes and pipes.
U.S. Pat. No. 576,425 to Bilton et al discloses an appliance for scraping interiors of water mains or pipes including a screw-threaded spindle with two cones mounted thereon. Lever-like cutter blades mounted on each of the cones are expanded and contracted by stout rubber washers and regulating nuts mounted on the spindle behind the cutter blades. Thus, a scraping power of the cutter blades is obtained by adjusting each of the regulating nuts, which respectively bear on the rubber washers, for, in turn, bearing on the cutter blades.
U.S. Pat. No. 5,305,488 to Lyle similarly discloses a tube-cleaning tool having a central shaft and two truncated-cone-shaped cutters with cutter blades, mounted thereon. In this regard, each of the cutters has a hole through a central axis thereof through which the shaft passes so that the cutters can slide along the shaft. Also mounted on the central shaft, one adjacent each respective cutter, are flexible bushings to press against the cutters and exert outward pivoting pressure on the lever-like cutter blades, as in Bilton et al. In Lyle, the cutters can slide along the shaft and press against each other, so that adjustment of cutter blades of both cutters with one adjustment is allowed. The shaft used to secure the cutters and flexible bushings to one another is formed with a twist in order to offset the two cutters with respect to one another. The Lyle device is propelled through an interior of a tube by fluid projected against a separate tail portion on the device. The tail portion is formed with openings that allow some fluid to flush through the tail portion to the cutter blades of the device. The Lyle device can be formed with a flexible shaft to enable it to move through "U" bent tubing.
Other similar lever-blade expandable tube, or pipe, cleaning devices are disclosed in U.S. Pat. Nos. 1,122,246 to Beam; 1,608,347 to Thompson et al; 1,612,842 to Thompson et al; 2,402,796 to Wood; 2,636,202 to Hinzman; and 4,891,115 to Shishkin et al.
There are several difficulties with these tube cleaning devices. For one thing, it is very difficult and expensive to refurbish scraper blades thereof when they become worn because they attach to and lever from hubs. Also, it is difficult to control, and to make uniform, forces exerted by their scrapers on interior walls of tubes because the pressures their scrapers exert depend upon flexibilities of cutter blades as well as on force applying mechanisms at the hubs, including in some cases the elasticities of rubber washers, or bushings. In this regard, in both Bilton et al and Lyle, as resilient members are compressed, lever cutting blades pivot outwardly from central axis areas, or hubs (cones), thereby causing exaggerated motion of outer scraping areas of the lever cutting blades. This aggregated motion, along with the flexibility of the lever cutter blades, makes it difficult to achieve a predictable final adjusted movement and a predictable scraping pressure.
It is an object of this invention to provide an adjustable tube-cleaner device that can be manufactured and assembled simply and economically, that can be economically refurbished, and that can be reliably and accurately adjusted to produce a predictable scraping pressure with a fine movement adjustment.